SDH Major Operational Components Summary ... - Christiealwis.com

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• Regenerator Section Overhead – The Regenerator Section Overhead contains only the information required for the elements located at both ends of a section. – The Regenerator Section Overhead is found in the first three rows of Columns 1 through 9 x N of the STM-N, N ≥ 1 frame. • Multiplex Section Overhead – The Multiplex Section Overhead contains the information required between the multiplexer section termination equipment at each end of the Multiplex section. – The Multiplex Section Overhead is found in Rows 5 to 9 of Columns 1 through 9 x N of the STM-N, N ≥ 1 frame. • Path Overhead – Discussed earlier 77 9 rows * ∆ STM-1 Regenerator section overhead (RSOH) & Multiplex Section Overhead (MSOH) A1 B1 D1 B2 D4 D7 D10 S1 A1 ∆ ∆ A1 A2 A2 A2 ∆ ∆ E1 D2 B2 B2 K1 D5 D8 D11 9 bytes ∆ ∆ J0 F1 D3 Administrative Unit pointer(s) Unscrambled bytes K2 D6 D9 D12 M1 E2 Bytes reserved for national use * * T1543290-01 RSOH MSOH The content of these reserved bytes has to be carefully selected as they are not scrambled. Media-dependent bytes NOTE – All unmarked bytes are reserved for future international standardization (for media-dependent, additional national use and other purposes). • A1 and A2 - Framing • J0 - Regenerator Section (RS) Trace message • B1 - RS bit interleaved parity code (BIP- 8) byte • E1 - RS orderwire byte • F1- RS user channel byte • D1, D2, D3 - RS Data Communications Channel (DCC) bytes • B2 - Multiplex Section (MS) bit interleaved parity code (MS BIP-24) byte • K1 & K2 - Automatic Protection Switching (APS channel) bytes • D4 to D12 - MS Data Communications Channel (DCC) bytes S1- Synchronization status message byte (SSMB) • M1- MS remote error indication • E2 - MS orderwire byte 78 2
Regenerator Section Overhead • A1 and A2 - Framing bytes – These two bytes indicate the beginning of the STM-N frame. The A1, A2 bytes are unscrambled. A1 has the binary value 11110110, and A2 has the binary value 00101000. The frame alignment word of an STM-N frame is composed of (3 x N) A1 bytes followed by (3 x N) A2 bytes. • J0 - Regenerator Section (RS) Trace message – It’s used to transmit a Section Access Point Identifier so that a section receiver can verify its continued connection to the intended transmitter. The coding of the J0 byte is the same as for J1 and J2 bytes. • Z0 - These bytes, which are located at positions in STM-N signal (N > 1), are reserved for future international standardization. • B1 - RS bit interleaved parity code (BIP-8) byte – This is a parity code (even parity), used to check for transmission errors over a regenerator section. Its value is calculated over all bits of the previous STM-N frame after scrambling, then placed in the B1 byte of STM-1 before scrambling. • E1 - RS orderwire byte – This byte is allocated to be used as a local order wire channel for voice communication between regenerators. • F1- RS user channel byte – This byte is set aside for the user’s purposes; it can be read and/or written to at each section terminating equipment in that line. • D1, D2, D3 - RS Data Communications Channel (DCC) bytes – These three bytes form a 192 kbit/s message channel providing a message-based channel for Operations, Administration and Maintenance (OAM) between pieces of section terminating equipment. The channel can be used from a central location for control, monitoring, administration, and other communication needs. 79 Multiplex Section Overhead • B2 - Multiplex Section (MS) bit interleaved parity code (MS BIP-24) byte – This bit interleaved parity N x 24 code is used to determine if a transmission error has occurred over a multiplex section. It’s even parity, and is calculated overall bits of the MS Overhead and the STM-N frame of the previous STM-N frame before scrambling. • K1 and K2 - Automatic Protection Switching (APS channel) bytes – These two bytes are used for MSP (Multiplex Section Protection) signaling between multiplex level entities for bidirectional automatic protection switching and for communicating Alarm Indication Signal (AIS) and Remote Defect Indication (RDI) conditions. K1 Byte K2 Byte Bits 1-4 Type of request Bits 1-4 Selects channel number – 1111 Lock out of Protection Bit 5 Indication of architecture – 1110 Forced Switch 0 1+1 – 1101 Signal Fail – High Priority 1 1:n – 1100 Signal Fail – Low Priority Bits 6-8 Indicate mode of operation – 1011 Signal Degrade – High Priority 111 MS-AIS – 1010 Signal Degrade – Low Priority 110 MS-RDI – 1001 (not used) 101 Provisioned mode is bi-directional – 1000 Manual Switch 100 Provisioned mode is unidirectional – 0111 (not used) 011 Future use – 0110 Wait-to-Restore 010 Future use – 0101 (not used) 001 Future use – 0100 Exercise 000 Future use – 0011 (not used) – 0010 Reverse Request – 0001 Do Not Revert – 0000 No Request Bits 5-8 Indicate the number of the channel requested 80 3
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Page 5 and 6: 1+1 Protection Switching 1+ N Prote
Page 7 and 8: TUG-3 structure 87 When mapped from

SDH Major Operational Components Summary ... - Christiealwis.com

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